The invention relates to a digital transmission system comprising a transmitter for transmitting and a receiver for receiving, via a transmission medium, digital signals representing a wide-band digital signal, for example, a digital audio signal sampled with a specific sample frequency F.sub.s. The transmitter has an input terminal for receiving the wide-band digital signal, which input terminal is coupled to an input of a first encoder. The first encoder includes a subband coder responsive to the wide-band digital signal to generate a plurality of M subband signals with sample frequency reduction, for which purpose the subband coder divides the wide-band digital signal into successive subbands having band numbers m which increase as the frequency increases, where 1.ltoreq.m.ltoreq.M; a quantization unit for the blockwise quantization of the respective subband signals to produce quantized samples in the signal blocks, a subband signal being composed of consecutive signal blocks, each signal block comprising q samples; and a bit allocation unit for generating bit allocation information specifying the number of bits representative of each of the q samples in a signal block. The transmitter further comprises a scale-factor information determiner for determining information related to a scale factor belonging to each signal block of a subband signal; a combining unit for combining the quantized samples in the signal blocks, the scale factor information and the bit allocation information in a frame of a second digital signal formed by successive frames; a second encoder for converting the second digital signal into a third digital signal so as to enable the third digital signal to be transmitted via the transmission medium; and an application unit for applying the third digital signal to the transmission medium. The receiver comprises a receiving unit for receiving a replicated third digital signal from the transmission medium which substantially corresponds to the third digital signal; a first decoder for converting the replicated third digital signal into a replicated second digital signal which substantially corresponds to the second digital signal; a derivation unit for deriving the quantized samples in the signal block, the bit allocation information and the scale factor information from frames in the replicated second digital signal to produce replicated subband signals; and a synthesis filter unit responsive to the replicated subband signals to construct a replica of the wide-band digital signal, which synthesis filter unit combines the subbands to the signal band of the wide-band digital signal with a sample frequency increase. The invention also relates to a transmitter and to a receiver to be used in the transmission system.
A transmission system of the type defined in the opening paragraph is known from European Patent Application No. 04.02.973, which corresponds to U.S. patent application Ser. No. 07/997,158, filed Dec. 21, 1992, and is incorporated herein by reference. The known system is a recording and reproducing system of the DCC type, in which a digital audio signal is recorded in one or more tracks on a magnetic record carrier. Another possible field of use of the invention is digital transmission, such as digital audio broadcasting (DAB).